Alliance Airlines has commenced tiller inspections across its Fokker F100 fleet after a report by the Australian Transport Safety Bureau found a damaged tiller to be the cause of a taxiing runway excursion.
On 28 September 2021, an Alliance Fokker F100 experienced a minor runway excursion of its nose wheel after completing a scheduled passenger flight from Perth to Laverton, with 75 passengers, three cabin crew and two flight crew onboard.
According to the final ATSB report, the captain took control of the aircraft after landing at Laverton, in order to taxi towards the end of the runway and complete the routine backtrack manoeuvre.
The captain commenced a right turn by rotating the tiller – the handwheel inside the cockpit that controls the aircraft’s nose wheel on the ground – however, reported being unable to achieve full tiller rotation, even when using the force of both hands.
The captain then attempted to tighten the turn by applying the right inboard brake and asymmetric thrust, however, was still unable to turn as expected.
The crew decided to continue the turn, which saw the aircraft’s nose wheel briefly leave the side of the runway onto the runway strip, risking damage to the aircraft. The aircraft then returned to the runway and taxied to the terminal.
According to the ATSB, a post-flight inspection identified damaged insulation in the nose wheel area and a torn universal joint boot on the tiller shaft.
ATSB Director Transport Safety Stuart Macleod said the torn boot on the universal joint “probably restricted the operation of the aircraft’s nose wheel steering system, preventing the aircraft from completing the turn on the runway”.
However, the ATSB questioned the flight crew’s decision to continue its turn, knowing that it would likely result in a runway taxiing excursion.
The flight crew later reported this decision was made based on their knowledge of the ground next to the runway being compact dirt, and the fact the airport had a single runway and no ground support equipment, so stopping would prohibit other aircraft from landing.
“In continuing the turn, the nose wheel left the runway surface and entered the runway strip, increasing the risk of damage to the aircraft,” Macleod said.
“While there was no damage to the aircraft, there was no assurance that the runway strip was clear of hazardous debris and could safely manoeuvre on the strip.”
Macleod noted that other aircraft would have in fact been unable to safely land if the Fokker had remained on the runway.
“But options such as having the airport staff inspect the runway strip before completing the turn onto it were available,” Macleod said.
“This incident highlights that when flight crews encounter an unexpected event and there is sufficient time to assess available options, they should utilise available resources to determine the safest course of action.”
In addition to encouraging flight crew to utilise available resources, such as having airport staff inspect the runway strip for debris that could inflict damage to the aircraft prior to the excursion, Alliance Airlines has also begun inspections across its Fokker F100 fleet, as a precaution.
The ATSB said the carrier has commenced a fleet-wide inspection of the tiller assembly universal boot joints across its Fokker F100 fleet, with inspections expected to be completed by February 2022.